Column Flotation

Eriez has more than 900 Column Cells operating worldwide

The Eriez Flotation Division has supplied more than 900 flotation columns throughput the world in mineral concentrating and purification applications that include iron ore, base-metals, gold, industrial minerals, fertilizers (phosphate and potash), energy (coal and oil-sands) and specialty applications such as oil/water separation.


EFD’s Advantages in Columns include:

  • A large group of knowledgeable engineers throughout the world to design and support your application.  This includes more than 20 years of experience in supplying column applications.
  • Offering test-services.  We operate a central test lab and test columns that can be brought to site that can be used to predict metallurgical performance and de-risk the installation.
  • Provides a variety of column and sparging technologies so we can recommend and design the most appropriate equipment for the application.  In some cases, we have optimized columns for particular mineral systems such as the PhosPro™ for phosphate, the K-Pro™ for potash, the BitPro™ for bitumen, and the CoalPro™ for coal

 Laboratory-scale Column units are available for small-scale testing on Eriez' Lab Equipment website.

 

Applications:

  • Coal

    CoalPro®, and StackCell™ are a few of Eriez column and hybrid flotation technologies engineered for the coal industries.

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  • COLUMN CELLS AS ROUGHERS

    Columns are often discounted as roughers because of the beliefs that a) mechanical cells will provide a higher level of recovery, and, b) higher recovery provides more revenue than higher grades. For simple ores, this is may be true. For more complex ores containing impurities which translate into additional treatment and refining charges, or for mines located in very remote regions, the benefit of being able to produce high grade concentrates even at the expense of a slight reduction in recovery, may make economic sense.

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  • MINERALS PROCESSING

    Eriez Flotation excels across the spectrum from ultra fines recovery to coarse particle separation in a wide range of mineral processing applications.

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Phosphate Producers Improve Plant Performance Using EFD Flotation Technology

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Mineral Producers Improve Plant Performance Using Column Flotation Technology

Paper includes Column Flotation technology benefits and description.
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The Production of High Grade Iron Ore Concentrates Using Flotation Columns

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The Use of Column Flotation for the Recovery of Ultra-Fine Phosphates

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Testing of the HydroFloat Separator for Coal Cleaning Applications

This article describes the theoretical basis for the development of the HydroFloat separator and provides an overview of performance data obtained from recent field trials.
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Industrial Applications for Column Cells as Roughers

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Flotation Technology for Coarse and Fine Particle Recovery

Challenges associated with conventional froth flotation equipment
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DeGrussa Profile CavTube Sparging

Ultra fines recovery of Copper Sulfide
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Improved Cleaner Circuit Performance at the DeGrussa Copper Mine With an In Situ Column Sparging System

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Spargers for Air/O2 Injection into CIP/CIL Gold Leach Tanks

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Reporte de Cavitador Eriez Articulo (003)

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Photos


Basic Idea

Flotation column cells are flotation act as three phase settlers where particles move downwards in a hindered settling environment counter-current to a flux of rising air bubbles that are generated by spargers located near the bottom of the cell.  The sparger technology is an important design choice, and allows the user to optimize the performance based on the feed characteristics (size distribution and liberation class).  Within the vessel there is a distribution of particle residence times dependent on settling velocity that may impact on the flotation of large particles.  Mechanically agitated cells do not suffer from this effect to the same degree but do require high energy input, on the order of 1 kW/m3 to suspend larger particles.  For feed with very large particles, the HydroFloat®, which is a modified flotation column has been developed.


The mechanism of particle/bubble collision in columns is different from intensive mixing devices such as mechanically agitated cells. Under the low-intensity mixing caused only by a rising bubble field, particle drift from the fluid streamlines is caused mainly by gravity and inertial forces and also by interception.  In mechanical cells, according to many researchers, bubble-particle collision occurs by their relative movement within turbulent vortices or at their boundaries.  Also, as velocities of both bubbles and particles during the attachment are slower under quiescent conditions in a column, the contact time is generally higher.  Therefore, probabilities of both collision and adhesion (components of attachment probability) are different than those in the mechanically agitated flotation process.

 

A column can support a deep froth bed and may use wash water to maintain a downward flow of water (positive bias) evenly across the cross-section of the vessel.  This essentially eliminates the entrainment of hydrophilic particles in the float product when the vessel is used for solid/solid separation. This property, along with the absence of stray flows of feed material to the float product from turbulence, means that column devices are normally superior to impeller type machines for the selective separation of fine particles (high grade). 

The bubbles used in a column are usually generated within the size range that maximizes interfacial surface flux and collection intensity through the vessel. In mechanical cells bubbles are usually generated by the shear action of the impeller; thus, bubble size is dependent on both airflow rate and impeller rotation speed. As such, bubble size cannot be controlled independently of cell turbulence. 
The height to diameter ratio of a column is significantly higher than mechanical machines. As a result control and consistency of flow is more critical. The column requires much less floor space to operate. 



Metallurgical benefits can be derived in a number of ways. In some cases the metallurgical benefits may be obvious. Improved concentrate grades, improved recoveries and reduced reagent consumption are some of the benefits attributed to column cells. In other cases the benefits may be less clear. With some ores, for example, it is possible to recover a portion of the valuable mineral into a high grade concentrate directly at the rougher stage, thereby reducing the size of the subsequent treatment stages. 

Operating cost savings can be realized from reduced power consumption, reduced maintenance costs and in some cases reduced reagent consumption.  Power costs can be 40 - 50% lower than an equivalent mechanical flotation circuit. Using column flotation it is possible to simplify the process by replacing two to three cleaner stages and associated transfer pumps with a single column producing final concentrate.

Reagent savings depend on the nature of the ore being treated and the reagent scheme being utilized. The most significant reductions usually occur with depressants, where it is possible to use wash water to lower impurity levels.

Column cells have very low maintenance requirements and low inventory requirements.